Gas scrubbing system

ABSTRACT

An aqueous organic amine acid gas scrubbing system, particularly an aqueous N-methyldiethanolamine or diethanolamine acid gas scrubbing system having incorporated therein (1) a compound or mixture of compounds having the formula ##STR1## wherein n is an integer from 1 to 3, m is an integer from 2 to a number sufficient to yield a molecular weight of about 800, R 1 , R 2 , R 3  and R 4  are each independently selected from the group consisting of --H, --C n&#39;  H 2n&#39;  OH, --C n&#39;  H 2n&#39;+1 , --C n&#39;  H 2n&#39;  N(R 3 )R 4  wherein n&#39; is an integer from 1 to 2 and wherein R 1  -R 3  and R 2  -R 4  may be joined to form cyclic amines when n is 2; said compound being present in about 10 to about 2000 parts per million parts of treating solution; (2) copper or a copper ion yielding compound in from 0 to 1000 ppm; and (3) sulfur or a sulfur atom yielding compound in from 0 to 1000 ppm.

BACKGROUND OF INVENTION

Natural and synthetic gases containing acidic components such as CO₂, H₂ S, COS, and the like, have been treated on a commercial scale with aqueous alkanolamine solutions to remove the acidic components. The severe corrosion which results from the presence of these components, particularly in the rich absorbent solution regeneration section, has necessitated keeping the concentration of the amine low, i.e., 10-30 percent generally and the loading, i.e. the amount of H₂ S/CO₂, in the absorbent solution, low. In light of the recent energy shortage and necessity to conserve energy it would be advantageous to more heavily load the gas treating solutions with the acidic components. It would be a further advantage to employ more concentrated absorbent solutions. However to accomplish these objects it is necessary to prevent any increase in corrosion and it would be more advantageous to reduce the corrosion to less than that experienced today at the lower loadings and solution concentrations.

A brief review of the prior art discloses that numerous patents have taught various polyamines as corrosion inhibitors for various fluids:

For example, Dickson et al. in U.S. Pat. No. 3,262,791, which is representative of many patents in the corrosion inhibitor field issued to Petrolite Corporation, describes polyalkylenimines of molecular weight above 800 as useful in preventing corrosion of iron, steel and ferrous alloys when using slushing oils. The patent also suggests these polyalkylenimines as capable of imparting corrosion resistance to brines, weak inorganic acids, organic acids, CO₂, H₂ S, etc.

Ting Sin Go in U.S. Pat. No. 3,819,328, also a Petrolite patent, discloses alkylene polyamines, such as ethylene diamine, to control acid corrosion in distillation columns, such as occurs in petroleum distillation columns. Preferably the alkylene polyamine is used in conjunction with a corrosion inhibitor, e.g., a film-forming corrosion inhibitor, i.e., morpholine, at regulated pH's of about 2. The corrosion of columns which have water condensers and which water has a high pH due to acidic materials such as H₂ S, HCN, CO₂, HCl, etc. is taught to be controlled.

Ulrich et al. in U.S. Pat. No. 2,143,393 discloses absorbing acid gases in an aqueous solution of a polymerized alkylenimine.

Johnson et al. in U.S. Pat. No. 3,137,654 teach using glycines as a corrosion inhibitor in an alkanolamine solution used to absorb CO₂ from industrial gases.

Yeakey et al. in U.S. Pat. No. 3,829,494 teach using a water-soluble trialkanolamine in an aqueous 2-(2-aminoethoxy)ethanol gas scrubbing medium.

Singh in U.S. Pat. No. 3,535,260 teaches a similar result for monoethanolamine gas treating solutions.

The art is rife with disclosures of nitrogen containing compounds useful as corrosion inhibitors, but that only a few are commercially acceptable. It is evident to one skilled in the art operating a commercial installation that the old limitations on concentration of absorbent, loading of the absorbent solution, etc., while improved to some extent with these few commercially accepted inhibitors are lacking in ability to carry without excessive corrosion the demands for more efficient operation, higher absorbent concentrations and higher loading, brought on by the energy shortage.

Is is therefore an object of the present invention to provide an inhibitor for aqueous amine gas absorbing systems which will enable higher concentrations of the amine absorbent to be used as well as a higher loading of the acid gases in the absorbent with reduced corrosion.

These and other advantages of the present invention will be apparent to those skilled in the art from the following disclosure and claims.

BRIEF DESCRIPTION OF INVENTION

In accordance with the present invention, a gas scrubbing solution, e.g., an aqueous alkanolamine solution, particularly, diethanolamine and N-methyldiethanolamine solutions, is rendered less corrosive toward metals, particularly ferrous metal and their alloys by incorporating into the solution from about 10 to about 3000 parts of an inhibitor composition consisting essentially of (1) from 10 to 2000 ppm of a compound having the formula ##STR2## wherein n is an integer from 1 to 3, m is an integer from 2 to an integer sufficient to yield a molecular weight of about 800; each R represents an independently selected member from the group consisting of --H, --C_(n') H_(2n') OH; --C_(n') H_(2n'+1) ; C_(n') H_(2n') N(R₃)R₄ ; wherein n' is an integer from 1 to 2 and wherein R₁ -R₃ and R₂ -R₄ may be joined together to form cyclic amines when n' is 2; (2) copper or a copper ion yielding compound in from 0 to 1000 ppm; and (3) sulfur or a sulfur atom yielding compound in from 0 to 1000 ppm.

Amine compounds falling within the scope of the formula set out above are for example, polyethylenimine (polyethylene polyamines) having molecular weights from about 60 to about 800 which may be mixtures of several amines, for example a commercial polyalkylene polyamine identified as EA-10 (or E-100) containing 8-9 weight percent tetraethylenepentamine, 30-35 weight percent pentaethylenehexamine, 55 weight percent hexaethyleneheptamine and the remainder branched and cyclic isomers, polyethylenimines, PEI 3 (molecular weight 300±50), PEI 6 (molecular weight about 600), EA-17 tris(aminoethyl)amine (about 90 percent branched), EA-19 pentaethylenehexamine (MW about 232), EA-15 (a mixture of 35-45 percent diethylenetriamine, 10-15 percent triethylenediamine, 5-15 percent piperazine), EA-25 (reaction product of triethylenetetramine divinylbenzene), EA-26 (a divinylbenzene-ethylvinylbenzene-diethylenetriamine mixture), EA-11 (aminoethylpiperazine-diethylenetriamine mixture), 1,2-polypropylenimine, tetraethylenepentamine, triethylenetetramine, diethylenetriamine, ethylenediamine, dihydroxyethyl ethylenediamine, and the like.

Copper metal or a copper ion yielding compound such as CuCO₃, or the like may be employed. (Get scope from earlier case.)

Sulfur or a sulfur ion yielding compound may be present and is present in those compositions containing H₂ S, COS or other sulfur containing constituents.

The inhibitors are most effective in diethanolamine solutions where the H₂ S to CO₂ ratio is 10/1 to 1/10, respectively. The inhibitors reduce corrosion compared to present day inhibitors in systems containing up to 1/40 H₂ S/CO₂, respectively. The absorbents DEA and MDEA are effectively provided with less corrosion than present day inhibitor systems with H₂ S only but the results are not as dramatic as when CO₂ is present also.

The alkanolamines which have been employed as absorbents for the acidic gas are the mono C₂₋₃ alkanolamines, such as monoethanolamine, monisopropanolamine, the dialkanol C₂₋₃ amines, such as diethanolamine and their N-alkyl substituted derivatives, i.e., methyl diethanolamine. The dialkanolamines show marked improvement in corrosion protection when the inhibitors of the present invention are employed.

DETAILED DESCRIPTION OF THE INVENTION PROCEDURE

The laboratory data were obtained from tests run in a modified Sparkler Filter at 40 psig, at a temperature at 125° C for about 17 hours. All 1020 mild steel test specimens (which were acid etched in 5N HCl, soap washed, water and acetone rinsed and weighted) were placed in 4 oz bottles containing the prospective inhibitor and 50% diethanolamine (DEA) -50 percent water, saturated with H₂ S/CO₂ at various gas ratios. The total liquid volume in each bottle at the start of the experiment was 120 mls. At the end of the experiment, the mild steel specimens were again etched in acid (containing HCl inhibitor) washed with soap and water and acetone rinsed and weighed. The corrosion rate and percent inhibition were calculated using the before and after weighing of the mild steel specimens according to the following equations:

    corrosion rate/yr = (534 W/DAT)

where W = weight loss in mg; D = density of specimen in gm/cc; A = area in square inches; and T = exposure in hours. ##EQU1##

Each of the following tables tabulate the experiments conducted and the results obtained in a single series of tests. The corrosion rate for the uninhibited, blank tests was run for each series to enable a direct comparison to be made with the other tests run in that series.

                                      TABLE I                                      __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 9/I                                                                             Corrosion                                                                            Percent                                      COmpound         PPM PPM                                                                               PPM Rate MPY                                                                             Inhibition                                   __________________________________________________________________________      1. Blank                   31.54                                               2. Blank                   31.78                                               3. Blank                   31.32                                               4. CuCO.sub.3   100        14.09 55.3                                          5.  "           100        12.84 59.3                                          6.  "           1000       9.70  69.3                                          7.  "           1000       10.09 68.0                                          8. CuCO.sub.3 + 10 cc MEA.sup.(1)                                                              100        5.48  82.6                                          9.  "           100        4.38  86.1                                         10.  "           1000       4.69  85.1                                         11.  "           1000       4.78  84.9                                         12. CuCO.sub.3 + 10 cc MEA.sup.(1) + S°                                                  100    100 5.55  82.4                                         13.  "           100    100 5.24  83.4                                         14.  "           1000   100 4.69  85.1                                         15.  "           1000   100 4.55  85.6                                         16.  "           100    1000                                                                               4.71  85.1                                         17.  "           100    1000                                                                               6.65  78.9                                         18. S°           100 36.48 -15.6                                        19. "                   100 33.82 -7.2                                         20. 10 cc MEA.sup.(1)       33.11 -4.9                                         21.  "                      30.84 2.2                                          22. PEI 6.sup.(2)                                                                               100        4.06  87.1                                         23.  "           100        4.22  86.6                                         24.  "           1000       2.82  91.1                                         25.  "           1000       2.04  93.5                                         __________________________________________________________________________      .sup.(1) MEA - monoethanolamine                                                .sup.(2) PEI 6 - polyethylenime molecular weight about 600               

RESULTS

Observation of data from 6 tests shows compounds PEI 6, CuCo₃ + 10 cc MEA, E-100, and E-100 + CuCO₃ + S° as very good protectors of mild steel specimen in 50 percent aqueous DEA solutions and an H₂ S/CO₂ environment. Passivation was observed from 84 percent to 96 percent inhibition. E-100 offers protection at concentrations as low as 1 ppm with 74 percent inhibition; and with the addition of CuCO₃ + S° an additive effect is seen with passivation around 96 percent to 97 percent.

                                      TABLE II                                     __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 9/1                                                                            Corrosion                                                                            Percent                                       Compound          PPM                                                                               PPM                                                                               PPM                                                                               Rate MPY                                                                             Inhibition                                    __________________________________________________________________________      1. Blank                  40.91                                                2. Blank                  40.59                                                3. Blank                  39.97                                                4. PEI 6.sup.(1)  100     3.76  90.7                                           5.  "             100     2.50  93.8                                           6.  "            1000     2.09  94.8                                           7.  "            1000     5.53  86.4                                           8.  "            2000     5.11  87.4                                           9.  "            2000     5.64  86.1                                          10. PEI 6.sup.(1) + CuCO.sub.3                                                                    100                                                                              1000  3.34  91.7                                          11.  "             100                                                                              1000  3.23  92.0                                          12.  "            1000                                                                               100  2.29  94.3                                          13.  "            1000                                                                               100  2.82  93.0                                          14.  "            1000                                                                              1000  3.12  92.3                                          15.  "            1000                                                                              1000  2.82  93.0                                          16. PEI 6.sup.(1) + CuCO.sub.3 + S°                                                       1000                                                                               100                                                                              1000                                                                              3.03  92.5                                          17.  "            1000                                                                               100                                                                              1000                                                                              2.20  94.6                                          18.  "            1000                                                                              1000                                                                               100                                                                              2.71  93.3                                          19.  "            1000                                                                              1000                                                                               100                                                                              2.72  93.3                                          20. CuCO.sub.3        100  12.63 68.8                                          21.  "                100  13.36 67.0                                          22.  "               1000  12.42 69.3                                          23.  "               1000  13.89 65.7                                          24. CuCO.sub.3 + Co(OAc).sub.2                                                                   1000                                                                              1000  11.18 72.4                                          25.  "            1000                                                                              1000  10.54 74.0                                          26. PEI 6.sup.(1) + Co(OAc).sub.2                                                                1000                                                                              1000  4.49  88.9                                          27.  "            1000                                                                              1000  23.06 43.1                                          28. Co(OAc).sub.2 1000     25.37 37.3                                          29.  "            1000     24.52 39.4                                          30. Co(OAc).sub.2 + S°                                                                    1000                                                                               100  36.32 10.3                                          31.  "            1000                                                                               100  35.59 12.1                                          32. PEI 6.sup.(1) + CuCO.sub.3 + MEA 10 cc                                                       1000                                                                              1000  2.20  94.6                                          33.  "            1000                                                                              1000  2.50  93.8                                          __________________________________________________________________________      .sup.(1) PEI 6 a polyethylenimine of molecular weight of about 600       

                                      TABLE III                                    __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 9/1                                                                             Corrosion                                                                            Percent                                      Compound         PPM                                                                               PPM PPM Rate MPY                                                                             Inhibition                                   __________________________________________________________________________      1. Blank                   31.31                                               2. Blank                   31.98                                               3. Blank                   32.12                                               4. CuCO.sub.3      1000     8.33 73.8                                          5.  "              1000     8.70 72.6                                          6. Co(OAc).sub.2 + CuCO.sub.3 + PEI 6                                                          1000                                                                              1000                                                                               1000                                                                                2.73 91.4                                          7.  "           1000                                                                              1000                                                                               1000                                                                                2.57 91.9                                          8. E-100.sup.(1)                                                                               1000        1.99 93.7                                          9.  "           1000        2.14 93.3                                         10. E-100 + CuCO.sub.3                                                                          1000                                                                              1000     2.73 91.4                                         11.  "           1000                                                                              1000     2.21 93.0                                         12. E-100 + CuCO.sub.3 + PEI 6                                                                  1000                                                                              1000                                                                               1000                                                                                1.76 94.5                                         13.  "           1000                                                                              1000                                                                               1000                                                                                2.06 93.5                                         14. Cr(NO.sub.3).sub.3                                                                          1000       25.12 21.0                                         15.  "           1000       24.83 21.9                                         16. Cr(NO.sub.3).sub.3 +  KMNO.sub.4                                                            1000                                                                              <100    26.37 17.1                                         17.  "           1000                                                                              <100    28.00 11.9                                         18. Cd(OAc).sub.2                                                                               1000       31.98 -0.6                                         19.  "           1000       31.31 1.6                                          20. Cd(OAc).sub.2 + KMNO.sub.4                                                                  1000                                                                              <100    34.04 -7.0                                         21.  "           1000                                                                              <100    35.16 -10.5                                        22. Co(OAc).sub.2                                                                               1000       23.36 26.5                                         23.  "           1000       23.86 25.0                                         __________________________________________________________________________      .sup.(1) E-100 is a polyethylene polyamine mixture having a molecular          weight of about 250-300                                                  

                  TABLE IV                                                         ______________________________________                                         50% DEA H.sub.2 S/CO.sub.2 9/1                                                                                    Cor-  Per-                                                                     rosion                                                                               cent                                                                     Rate  Inhi-                                 Compound        PPM    PPM    PPM  MPY   bition                                ______________________________________                                          1. Blank                          20.52                                        2. Blank                          19.90                                        3. Blank                          21.64                                        4. E-100.sup.(1)                                                                               100               1.88  90.9                                   5.  "           100               1.88  90.0                                   6.  "          1000               1.47  92.9                                   7.  "          1000               2.02  90.2                                   8.  "          2000               1.88  90.9                                   9.  "          2000               1.73  91.6                                  10. E-100.sup.(1) + Co(OAc).sub.2.sup.(2)                                                      1000   1000        3.62  82.5                                  11.  "          1000   1000        1.82  91.2                                  12. E-100 + PEI 6                                                                              1000   1000        1.94  90.6                                  13.  "          1000   1000        2.02  90.2                                  14. E-100 + 10 cc MEA.sup.(3)                                                                  1000               2.02  90.2                                  15.  "          1000               1.53  92.6                                  16. 10 cc MEA.sup.(3)              27.69 -33.9                                 17.   "                            28.66 -38.6                                 18. PEI 6.sup.(3)      1000        2.72  86.9                                  19.  "                 1000        2.29  88.9                                  20. Co(OAc).sub.2      1000        14.40 30.4                                  21.  "                 1000        20.66 0.1                                   22. K-437.sup.(4)                                                                              1000               12.38 40.2                                  23.  "          1000               10.22 50.6                                  24. KW-12.sup.(5)                                                                              1000               9.32  54.9                                  25.  "          1000               9.67  53.2                                  ______________________________________                                          .sup.(1) E-100 a polyethylene polyamine mixture, avg. MW 250-300               .sup.(2) Co(OAc).sub.2 cobalt acetate                                          .sup.(3) MEA monoethanolamine                                                  .sup.(4) Commercial corrosion inhibitor for DEA and MEA manufactured by        Petrolite and sold under trade name K-437                                      .sup.(5) Commercial corrosion inhibitor for DEA and MEA manufactured by        Petrolite and sold under trade name KW-12                                

                  TABLE V                                                          ______________________________________                                         50% DEA H.sub.2 S/CO.sub.2 9/1                                                                               Corrosion                                                                               Percent                                 Compound  PPM     PPM    PPM  Rate MPY Inhibition                              ______________________________________                                         1.   Blank                      31.78                                          2.   Blank                      41.65                                          3.   Blank                      37.26                                          4.   E-100    10                7.60     79.4                                  5.   "        10                7.36     80.1                                  6.   "        50                7.13     80.7                                  7.   "        50                6.89     81.3                                  8.   "        100               7.82     78.8                                  9.   "        100     6.96 81.1                                                10.  "        1000              6.89     81.3                                  11.  "        1000              8.46     77.1                                  ______________________________________                                    

                                      TABLE VI                                     __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 1/1                                                                           Corrosion                                                                            Percent                                        Compound      PPM                                                                               PPM                                                                               PPM                                                                               PPM                                                                               Rate MPY                                                                             Inhibition                                     __________________________________________________________________________      1. Blank                 25.27                                                 2. Blank                 26.22                                                 3. Blank                 24.90                                                 4. E-100     1           6.55  74.3                                            5.  "        1           6.62  74.0                                            6.  "        10          5.67  77.8                                            7.  "        10          5.08  80.0                                            8.  "        100         1.70  93.3                                            9.  "        100         1.62  93.6                                           10.  "        1000        1.62  93.6                                           11.  "        1000        1.47  94.2                                           12. CuCO.sub.3 Lot 6750                                                                      100         7.96  68.7                                           13.  "        100         7.51  70.5                                           14.  "        1000        6.41  74.8                                           15.  "        1000        8.17  67.9                                           16. S° 100         22.62 11.2                                           17. "         100         23.73  6.8                                           18. "         1000        23.57  7.4                                           19. "         1000        22.39 12.1                                           20. E-100 + CuCO.sub.3 + S°                                                           1000                                                                               100  1000                                                                              0.97  96.2                                           21.   "       1000                                                                               100  1000                                                                              0.88  96.6                                           22.   "       1000                                                                              1000  1000                                                                              1.10  95.7                                           23.   "       1000                                                                              1000  1000                                                                              1.03  95.9                                           24. CuCO.sub.3 + S°                                                                      1000  1000                                                                              8.46  66.8                                           25.  "           1000  1000                                                                              8.10  68.2                                           __________________________________________________________________________

In the following tables, data is presented demonstrating the results achieved with various compounds falling within the scope of the invention as well as results obtained with closely related compounds and commercially available compositions. Abbreviations used hereinafter are set forth here to facilitate comprehension of the data.

    ______________________________________                                         Abbreviations                                                                  Code      Description                                                          ______________________________________                                         E-100     Polyethylene polyamine MW ca 250-300                                 PEI 6     Polyethylenimine avg. MW 600                                         EA-13     Distilled E-100                                                      EA-14     Bis(2-hydroxyethyl) piperazine                                       VE-1      Bis(2-aminoethyl ether)                                              EA-15     Ethyleneamine (NC2189L)                                              EA-17     Tris(2-aminoethyl)amine                                                        90% Branched 10% Linear                                              EA-19     Pentaethylenehexamine                                                EA-22     Aminated Polypropylene Glycol                                        EA-23     Dodecylamine + 2EO.sup.(1) + 4BO.sup.(2)                             EA-25     Triethylenetetraamine-                                                         Divinyl Benzene                                                                TETA-DVB Polymer                                                     EA-26     Ethylvinylbenzene (EVB)                                                        Divinylbenzene (DVB)                                                           Ethylvinylbenzene (EVB)                                                        Diethylenetriamine (DETA)                                                      Polymer                                                              EA-27     MeCl Quat, DVB-DETA                                                  EA-28     2-methyl Imidazoline                                                 EA-29     Piperazine                                                           EA-18     Dowell Corban 326                                                    EA-10     E-100                                                                DETA      Diethylenetriamine                                                   TRT3      Commercial inhibitor                                                 (KW-17)   Petrolite KW-17                                                      EA-75     Polyethylenimine (E-75)                                                        filtered solids from E-100                                           PEI 3     Polyethylenimine avg. MW 300                                         TEPA      Tetraethylenepentaamine                                              RCC-9     Tetradecylalkyl pyridinium bromide                                   FO-3      Commercial quaternary amine                                          SH-1      70 gm MEA, 3 g CuS, 15 gm S°                                  OA-70     Organic amine 70 a mixture of polyamines                                       sold by The Dow Chemical Company                                     ______________________________________                                          .sup.(1) EO - ethylene oxide                                                   .sup.(2) BO - 1,2-butylene oxide                                         

The data in each of the following tables was obtained using the indicated compound(s) in the manner set forth in Example 1.

PROCEDURE

A 50 percent solution of N-methyl diethanolamine (N-MDEA) was saturated with H₂ S/CO₂ gases at a ratio of 9/1. Prospective inhibitors for N-MDEA were tested in the same manner used to test compounds for diethanolamine (DEA) inhibition. The corrosion rate and percent inhibition were determined by the same method used for DEA.

                  TABLE VII                                                        ______________________________________                                         50% N-Methyl Dea H.sub.2 S/CO.sub.2 9/1                                                                                 Per-                                                                     Corro-                                                                               cent                                                                     sion  Inhibi-                               Compound        PPM    PPM    PPM  Rate  tion                                  ______________________________________                                         1.   Blank                           25.64                                     2.   Blank                           24.83                                     3.   Blank                           27.78                                     4.   EA-10 (E-100)   10              18.49 29.1                                5.   "               10              19.15 26.6                                6.   "               100             2.14  91.8                                7.   "               100             1.91  92.7                                8.   EA-75 (E-75)    10              21.45 17.8                                9.   "               10              23.64 9.4                                 10.  "               100             1.84  92.9                                11.  "               100             1.84  92.9                                12.  PEI-3           10              2.43  90.7                                13.  "               10              2.57  90.1                                14.  "               100             1.62  93.8                                15.  "               100             2.07  92.1                                16.  PEI-6           10              2.59  90.1                                17.  "               10              7.96  69.5                                18.  "               100             1.99  92.4                                19.  "               100             1.70  93.5                                20.  TRT-3 (KW-17)  1000             1.92  92.6                                21.  TRT-3 (KW-17)  1000             2.50  90.4                                22.  TRT-3 (KW-17)   100             6.99  7.32                                23.  TRT-3 (KW-17)   100             4.34  83.4                                24.  CuCO.sub.3            10        16.50 36.7                                25.  CuCo                  10        16.79 35.6                                26.  CuCO.sub.3 +S° 10   10   16.94 35.1                                27.  CuCO.sub.3 +S° 10   10   18.42 29.4                                28.  S°                  10   27.25 -4.5                                29.  S°                  10   27.03 -3.6                                30.  EA-10+CuCO.sub.3 +S°                                                                    10    10   10   2.28  91.3                                31.  EA-10+CuCO.sub.3 +S°                                                                    10    10   10   2.28  91.3                                32.  EA-75+CuCO.sub.3 +S°                                                                    10    10   10   2.59  90.1                                33.  EA-75+CuCO.sub.3 +S°                                                                    10    10   10   2.28  91.3                                34.  PEI-3+CuCO.sub.3 +S°                                                                    10    10   10   1.98  92.4                                35.  PEI-3+CuCO.sub.3 +S°                                                                    10    10   10   1.91  92.7                                36.  PEI-6+CuCO.sub.3 +S°                                                                    10    10   10   2.80  89.3                                37.  PEI-6+CuCO.sub.3 l +S°                                                                  10    10   10   2.90  85.0                                ______________________________________                                    

RESULTS AND DISCUSSION

The data, listed in Table VII, shows that those compounds which were effective in preventing corrosion in DEA, were just as effective in inhibiting corrosion in N-methyl DEA. At 100 ppm, the materials offered protection around 93 percent and the polyamine, CuCO₃ and S° synergistic system also showed excellent protection of mild steel.

                  TABLE VIII                                                       ______________________________________                                         50% DEA H.sub.2 S/CO.sub.2 9/1                                                                                  Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhibi-                                 Compound      PPM    PPM    PPM  MPY   tion                                    ______________________________________                                         1.   Blank                         42.06 10.5                                  2.   Blank                         46.64 0.7                                   3.   Blank                         52.24 -11.2                                 4.   E-100 (EA-10)                                                                               1000             1.84  96.1                                  5.   "            1000             1.47  96.9                                  6.   WS-1         1000             3.17  93.3                                  7.   "            1000             2.80  94.0                                  8.   EA-13        1000             2.06  95.6                                  9.   "            1000             2.28  95.1                                  10   EA-14        1000             53.11 -13.1                                 11.  "            1000             49.73 -5.9                                  12.  EA-15        1000             6.92  85.3                                  13.  "            1000             7.66  83.7                                  14.  EA-17        1000             1.99  95.8                                  15.  "            1000             2.51  94.7                                  16.  EA-19        1000             2.14  95.5                                  17.  "            1000             2.28  95.1                                  18.  EA-22        1000             56.36 -20.0                                 19.  "            1000             56.65 -20.6                                 20.  EA-23        1000             52.30 -11.3                                 21.  "            1000             47.89 -1.9                                  22.  EA-25        1000             8.91  81.0                                  23.  "            1000             8.10  82.7                                  24.  EA-26        1000             7.96  83.1                                  25.  "            1000             7.51  84.0                                       EA-29                                                                     26.  Piperazine   1000             29.46 37.3                                  27.  "            1000             28.88 38.5                                  28.  Diethyl-                                                                       enetriamine  1000             16.36 65.2                                  29.  "            1000             24.17 48.6                                  30.  EA-28        1000             59.52 -26.7                                 31.  "            1000             58.79 -25.1                                 32.  EA-18        1000             48.47 -3.2                                  33.  ∝     1000             48.32 -2.9                                  34.  EA-27        1000             10.16 78.4                                  35.  "            1000             10.24 78.2                                  ______________________________________                                    

                  TABLE IX                                                         ______________________________________                                         50% DEA H.sub.2 S/CO.sub.2 9/1                                                                                    Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhibi-                               Compound        PPM    PPM    PPM  MPY   tion                                  ______________________________________                                         1.   Blank                           35.95 -1.6                                2.   Blank                           33.89 4.2                                 3.   Blank                           36.32 -2.6                                4.   E-100            .5             6.92  80.4                                5.   "                .5             6.70  81.1                                6.   "               10              8.62  75.6                                7.   "               10              9.14  74.2                                8.   "              1000             1.10  96.9                                9.   "              1000             1.03  97.1                                10.  CuCO.sub.3      100             11.71 66.9                                11.  "               100             11.34 67.9                                12.  "              1000             9.22  74.0                                13.  "              1000             9.72  72.5                                14.  S°       100             26.97 23.8                                15.  "               100             29.61 16.3                                16.  "              1000             23.36 34.0                                17.  "              1000             23.73 32.9                                18.  CuCO.sub.3 +S°                                                                          100     100     11.49 67.5                                19   "               100    100      11.27 68.1                                20.  "              1000    100      10.16 71.3                                21.  "              1000    100      10.61 70.0                                22.  E-100+CuCO.sub.3                                                                               10     100      1.26  96.4                                23.  "               10     100      1.25  96.5                                24.  "               10    1000      1.54  95.6                                25.  "               10    1000      1.47  95.8                                26.  "              1000    100      1.18  96.7                                27.  "              1000    100      1.18  96.7                                28.  E-100+S°                                                                                10     100      8.25  76.7                                29.  "               10     100      8.04  77.3                                30.  "               10    1000      6.92  80.4                                31.  "               10    1000      5.68  84.0                                32.  "              1000    100      1.11  96.9                                33.  "              1000    100      1.26  96.4                                34.  E-100+CuCO.sub.3 +S°                                                                    10     100 100  1.47  95.8                                35.  "               10     100 100  1.33  96.3                                36.  "               10    1000 100  1.25  96.5                                37.  "               10    1000 100  1.33  96.3                                38.  "              1000    100 100  1.26  96.4                                39.  "              1000    100 100  1.25  96.5                                ______________________________________                                    

                  TABLE X                                                          ______________________________________                                          50% DEA H.sub.2 S/CO.sub.2 9/1                                                                                   Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhibi-                               Compound        PPM    PPM    PPM  MPY   tion                                  ______________________________________                                         1    Blank                           31.24 1.5                                 2.   Blank                           32.85 -3.6                                3.   Blank                           31.01 2.2                                 4.   E-100           1               12.68 60.0                                5.   "               1               14.51 54.2                                6.   "               10              2.72  91.4                                7.   "               10              2.80  91.2                                8.   "              100              1.33  95.8                                9.   "              100              1.33  95.8                                10.  CuCO.sub.3 in DEA.sup.(1)                                                                      10              14.30 54.9                                11.  "               10              14.59 54.0                                12.  CuCO.sub.3     100              12.81 59.6                                13.  "              100              12.38 61.0                                14.  S° in MEA.sup.(2)                                                                       10              28.14 11.2                                15.  "               10              27.33 13.8                                16.  S°      100              24.38 23.1                                17.  "              100              24.38 23.1                                18.  E-100+CuCO.sub.3                                                                               1      10       1.47  95.4                                19.  "               1      10       1.47  95.4                                20.  "               10     10       1.39  95.6                                21.  "               10     10       1.33  95.8                                22.  "               10    100       1.25  96.1                                23.  "               10    100       1.39  95.6                                24.  E-100 + CuCO.sub.3 +S°                                                                  1      10   10  1.76  94.4                                25.  "               1      10   10  1.78  94.4                                26.  "               10     10   10  1.33  95.8                                27.  "               10     10   10  1.47  95.4                                28.  "               10    100   10  1.25  96.1                                29.  "               10    100   10  1.26  96.0                                30.  "               10    100  1.54 95.1                                      31.  "               10    100  100  1.17  96.3                                32.  E-100+Co(OAc).sub.2                                                                            10    100       5.16  83.7                                33.  "               10    100       8.17  74.2                                34.  "               1     100       14.51 54.2                                35   "               1     100       15.76 50.3                                36.  E-100+Cr(NO.sub.3).sub.3                                                                       10    100       4.64  85.4                                37.  "               10    100       2.59  91.8                                38.  "               1     100       12.22 61.5                                39.  "               1     100       13.70 56.8                                ______________________________________                                          .sup.(1) 10 cc 50% aqueous DEA                                                 .sup.(2) 10 cc MEA                                                       

                                      TABLE XI                                     __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 9/1                                                                             Corrosion                                                                            Percent                                      Compound           PPM                                                                               PPM                                                                               PPM                                                                               Rate MPY                                                                             Inhibition                                   __________________________________________________________________________     1. Blank                    50.31 -0.6                                         2. Blank                    51.56 -3.1                                         3. Blank                    48.10 3.8                                          4. EDA Ethylenediamine                                                                             10      38.39 23.2                                         5. "                10      37.79 24.4                                         6. "               100      22.62 54.8                                         7. "               100      24.24 51.5                                         8. TETA Triethylenetetramine                                                                       10      32.63 34.7                                         9. "                10      29.91 40.2                                         10.                                                                               "               100      20.32 59.3                                            "               100      19.23 61.5                                            TEPA Tetraethylene pentamine                                                                    10      18.41 63.2                                            "                10      26.52 47.0                                            "               100      10.68 78.6                                            "               100      12.97 74.1                                            PEI-3            10      2.95  94.1                                            "                10      3.25  93.5                                            "               100      1.47  97.1                                            "               100      1.47  97.1                                         20.                                                                               EDA+CuCO.sub.3+S°                                                                        10                                                                               10 10 38.46 23.1                                            "                10                                                                               10 10 40.22 19.5                                            "               100                                                                               10 10 14.59 70.8                                            "               100                                                                               10 10 14.22 71.6                                            TETA+CuCO.sub.3 +S°                                                                      10                                                                               10 10 15.69 68.6                                            "                10                                                                               10 10 17.02 66.0                                            "               100                                                                               10 10 5.45  89.1                                            "               100                                                                               10 10 5.44  89.1                                            TEPA+CuCO.sub.3 +S°                                                                      10                                                                               10 10 4.87  90.3                                            "                10                                                                               10 10 4.79  90.4                                         30.                                                                               "               100                                                                               10 10 4.27  91.5                                            "               100                                                                               10 10 4.27  91.5                                            PEI-3+CuCO.sub.3 +S°                                                                     10                                                                               10 10 1.91  96.2                                            "                10                                                                               10 10 2.06  95.9                                            E-100+CuCO.sub.3 +S°                                                                     1 10 10 5.23  89.5                                            "                1 10 10 4.72  90.6                                         __________________________________________________________________________

                                      TABLE XII                                    __________________________________________________________________________     50% DEA H.sub.2 S/CO.sub.2 9/1                                                                          Corrosion                                                                            Percent                                         Compound        PPM                                                                               PPM                                                                               PPM                                                                               Rate MPY                                                                             Inhibition                                      __________________________________________________________________________     1. Blank                 29.02 -2.4                                            2. Blank                 28.07 0.9                                             3. Blank                 27.91 1.5                                             4. E-100         10      9.13  67.8                                            5. "             10      10.09 64.4                                            6. "            100      2.95  89.6                                            7. "            100      2.87  89.9                                            8. CuCO.sub.3 in 50% DEA                                                                        10      31.68 -11.8                                           9. "             10      38.97 -37.5                                           10.                                                                               "             100     11.42 59.7                                               "             100     9.43  66.7                                               Ni(NO.sub.3).sub."2 . 6H.sub.2 O                                                             10      27.85 1.7                                                "             10      28.80 -1.6                                               Bis(2-aminoethyl)ether                                                                      1000     14.51 48.8                                               "            1000     15.69 44.6                                               E-100+CuCO.sub.3                                                                             10                                                                                10   3.83  86.5                                               "             10                                                                                10   3.61  87.3                                               E-100 +CuCO.sub.3 +Ni.sup.+2                                                                 10                                                                                10                                                                               10 3.32  88.3                                               "             10                                                                                10                                                                               10 3.83  86.5                                            20.                                                                               (Bis(3-aminoethyl)ether +                                                      CuCO.sub.3   1000                                                                               10   10.76 62.0                                               "            1000                                                                               10   10.47 63.1                                               "            1000                                                                              100   3.68  87.0                                               "            1000                                                                              100   4.13  85.4                                               TRT-3 (KW-17)                                                                               1000     2.28  91.9                                               "            1000     1.91  93.3                                            __________________________________________________________________________

                                      TABLE XIII                                   __________________________________________________________________________     50% DEA CO.sub.2 /H.sub.2 S 10/1                                                                          Corrosion                                                                            Percent                                       Compound          PPM                                                                               PPM                                                                               PPM                                                                               Rate MPY                                                                             Inhibition                                    __________________________________________________________________________     1. Blank                   6.78                                                2. Blank                   5.81                                                3. Blank                   6.19                                                4. EA-10 (E-100)    1      3.16  49.6                                          5. "                1      3.09  50.6                                          6. "               10      1.11  82.2                                          7. "               10      1.18  81.1                                          8. "               100     0.66  89.4                                          9. "               100     0.66  89.4                                          10.                                                                               "              1000     0.52  91.7                                             "              1000     0.30  95.2                                             PEI-3           10      0.60  90.5                                             "               10      0.74  88.2                                             "              1000     0.52  91.7                                             "              1000     0.52  91.7                                             TRT-3          1000     0.96  84.7                                             "              1000     0.89  85.8                                             EA-10 + CuCO.sub.3 + S°                                                                 10                                                                               10  10                                                                               0.88  86.0                                             "               10                                                                               10   10                                                                              1.03  83.5                                          20.                                                                               PEI-3 + CuCO.sub.3 + S°                                                                 10                                                                               10  10                                                                               0.97  84.6                                             "               10                                                                               10  10                                                                               0.89  85.8                                             CuCO.sub.3 + S°                                                                         10                                                                               3     7.30  -16.5                                            "               10                                                                               10    7.51  -19.9                                            CuCO.sub.3      10      7.15  -14.2                                            "               10      7.00  -11.8                                            RCC-9 + NH.sub.4 SCN + EA-10                                                                   500                                                                              50 100                                                       65.9                                                                           "               500                                                                              50 100                                                                               1.76  71.8                                             RCC-9           500     6.26  -0.0                                             "               500     6.05  3.4                                           30.                                                                               NH.sub.4 SCN    50      6.26  -0.0                                             "               50      6.05  3.4                                              RCC:9 +NH.sub.4 SCN                                                                            500                                                                              50    5.82  7.0                                              " 500          50    5.82                                                                              7.0                                                    RCC-9 +NH.sub.4 SCN + EA-10                                                                    500                                                                              50  10                                                                               2.36  62.3                                             "               500                                                                              50  10                                                                               1.99  68.2                                          __________________________________________________________________________

                  TABLE XIV                                                        ______________________________________                                         70% DEA H.sub.2 S/CO.sub.2 9/1                                                                                  Corro-                                                                    sion cent                                                                           Rate  Inhibi-                                 Compound      PPM    PPM    PPM  MPY   tion                                    ______________________________________                                         1.   Blank                         28.44 1.7                                   2.   Blank                         29.38 -1.6                                  3.   Blank                         28.96 -0.1                                  4.   E-100         .5              13.78 52.4                                  5.   "             .5              15.18 47.5                                  6.   "             10              12.23 57.7                                  7.   "             10              11.86 59.0                                  8.   "            1000             1.76  93.9                                  9.   "            1000             10.53 63.6                                  10.  PEI-6          1              24.17 16.5                                  11.  "              1              24.39 15.7                                  12.  "             10              12.81 55.7                                  13.  "             10              12.38 57.2                                  14.  "            1000             1.84  93.6                                  15.  "            1000             1.76  93.9                                  16.  CuCO.sub.3 in MEA                                                                            10              21.29 26.4                                  17.  "             10              27.26 5.8                                   18.  CuCO.sub. 3   100             9.36  67.6                                  19.  "             100             9.66  66.6                                  20.  "            1000             5.52  80.9                                  21.  "            1000             5.45  81.2                                  22.  PEI-6+CUCO.sub.2                                                                             10     100      2.44  91.6                                  23.  "             10     100      2.15  92.6                                  24.  "            1000    100      1.55  94.6                                  25.  "            1000    100      1.54  94.7                                  26.  "             10    1000      1.76  93.9                                  27   "             10    1000      1.63  94.4                                  28.  E-100+CuCO.sub.3                                                                             10     10       10.82 62.6                                  29.  "             10     10       1.92  93.4                                  30.  "            1000    10  1.33 95.4                                        31.  "            1000    10       1.47  94.9                                  ______________________________________                                    

                  TABLE XV                                                         ______________________________________                                         50% MDEA CO.sub.2 /H.sub.2 S 50/1                                                                                 Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhib-                                Compound        PPM    PPM    PPM  MPY   ition                                 ______________________________________                                         1. Blank                           8.54   0.3                                  2. Blank                           8.54   0.3                                  3. Blank                           8.62  -0.6                                  4. EA-10        10                 0.66  92.3                                  5. EA-10        10                 1.03  87.9                                  6. EA-10        100                0.89  89.6                                  7. EA-10        100                0.88  89.8                                  8. EA-10        1000               0.81  90.6                                  9. EA-10        1000               0.81  90.6                                  10. EA-10 + CuCO.sub.3 + S°°                                                     10     10     10   1.33  84.5                                  11. EA-10 + CuCO.sub.3 + S°                                                             10     10     10   1.33  84.5                                  12. CuCO.sub.3 + S°                                                                     10     10          6.12  28.6                                  13. CuCO.sub.3 + S°                                                                     10     10          6.62  22.7                                  14. CuCO.sub.3  10                 7.44  13.2                                  15. CuCO.sub.3  10                 6.55  23.5                                  16. FO-3        1000               5.82  32.1                                  17. FO-3        1000               3.32  61.3                                  18. FO-6        1000               6.49  24.3                                  19. FO-3        1000               6.55  23.5                                  20. RCC-9       500                6.18  27.9                                  21. RCC-9       500                5.45  36.4                                  22. NH.sub.4 SCN                                                                               50                 5.97  30.3                                  23. NH.sub.4 SCN                                                                               50                 6.10  28.8                                  24. RCC-9 + NH.sub.4 SCN                                                                       500    50          5.01  41.5                                  25. RCC-9 + NH.sub.4 SCN                                                                       500    50          4.13  51.9                                  26. FO-3 + NH.sub.4 SCN                                                                        1000   50          3.25  62.1                                  27. FO-3 + NH.sub.4 SCN                                                                        1000   50          5.00  41.6                                  28. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     10   2.44  71.5                                  29. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     10   3.83  55.3                                  30. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     100  1.18  86.2                                  31. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     100  0.73  91.5                                  32. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     1000 0.89  89.6                                  33. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     1000 0.66  92.3                                  34. FO-3 + NH.sub.4 SCN +                                                        EA-10         1000   50     10   1.84  78.5                                  35. FO-3 + NH.sub.4 SCN +                                                        EA-10         1000   50     10   1.84  78.5                                  36. FO-3 +  SCN +                                                                EA-10         1000   50     100  0.96  88.8                                  37. FO-3 + NH.sub.4 SCN +                                                        EA-10         1000   50     100  0.96  88.8                                  ______________________________________                                    

                  TABLE XVI                                                        ______________________________________                                         30% MEA H.sub.2 S/CO.sub.2 9/1                                                                                    Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhib-                                Compound        PPM    PPM    PPM  MPY   ition                                 ______________________________________                                         1. Blank                           23.80  4.2                                  2. Blank                           24.97 -0.5                                  3. Blank                           25.79 -3.8                                  4. E-100        10                 10.24 58.8                                  5. E-100        10                 8.69  65.0                                  6. E-100        100                6.55  73.6                                  7. E-100        100                6.78  72.7                                  8. E-75         10                 10.84 56.4                                  9. E-75         10                 10.39 58.2                                  10. E-75        100                6.19  75.1                                  11. E-75        100                6.70  73.0                                  12. PEI-3       10                 4.42  82.2                                  13. PEI-3       10                 4.71  81.0                                  14. PEi-3       100                2.51  89.9                                  15. PEI-3       100                2.65  89.3                                  16. PEI-6       10                 7.73  68.9                                  17. PEI-6       10                 8.17  67.1                                  18. PEI-6       100                6.26  74.8                                  19. PEI-6       100                4.64  81.3                                  20. TRT-3       1000               7.37  70.3                                  21. TRT-3       1000               8.32  66.5                                  22. E-100 + CuCO.sub.3 + S°                                                             10     10     10   4.19  83.1                                  23. E-100 + CuCO.sub.3 + S°                                                             10     10     10   4.13  83.4                                  24. E-75 + CuCO.sub.3 + S°                                                              10     10     10   3.98  84.0                                  25. E-75 + CuCO.sub.3 "+ S°                                                             10     10     10   3.32  86.7                                  26. PEI-3 + CuCO.sub.3 + S°                                                             10     10     10   5.01  79.8                                  27. PEI-3 + CuCO.sub.3 + S°                                                             10     10     10   5.97  76.0                                  28. PEI-6 + CuCO.sub.3 + S°                                                             10     10     10   3.01  87.9                                  29. PEI-6 + CuCO.sub.3 + S°                                                             10     10     10   2.65  89.3                                  30. CuCO.sub.3 + S°                                                                            10     10   13.04 47.5                                  31. CuCO.sub.3 + S°                                                                            10     10   14.30 42.5                                  ______________________________________                                    

                  TABLE XVII                                                       ______________________________________                                         50% N-Methyl DEA H.sub.2 S/CO.sub.2 9/1                                                                           Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhib-                                Compound        PPM    PPM    PPM  MPY   ition                                 ______________________________________                                         1. Blank                           25.64 1.7                                   2. Blank                           24.83 4.8                                   3. Blank                           27.78 -6.5                                  4. E-100        10                 18.49 29.1                                  5. E-100        10                 19.15 26.6                                  6. E-100        100                2.14  91.8                                  7. E-100        100                1.91  92.7                                  8. E-75         10                 21.45 17.8                                  9. E-75         10                 23.64 9.4                                   10. E-75        100                1.84  92.9                                  11. E-75        100                1.84  92.9                                  12. PEI-3       10                 2.43  90.7                                  13. PEI-3       10                 2.57  90.1                                  14. PEI-3       100                1.62  93.8                                  15. PEI-3       100                2.07  92.1                                  16. PEI-6       10                 2.59  90.1                                  17. PEI-6       10                 7.96  69.5                                  18. PEI-6       100                1.99  92.4                                  19. PEI-6       100                1.70  93.5                                  20. TRT-3       1000               1.92  92.6                                  21. TRT-3       1000               2.50  90.4                                  22. TRT-3       100                6.99  73.2                                  23. TRT-3       100                4.34  83.4                                  24. CuCO.sub.3         10          16.50 36.7                                  25. CuCO.sub.3         10          16.79 35.6                                  26. CuCO.sub.3 + S°                                                                            10     10   16.94 35.1                                  27. CuCO.sub.3 + S°                                                                            10     10   18.42 29.4                                  28. S°                 10   27.25 -4.5                                  29. S°                 10   27.03 -3.6                                  30. E-100 + CuCO.sub.3 + S °                                                            10     10     10   2.28  91.3                                  31. E-100 + CuCO.sub.3 + S°                                                             10     10     10   2.28  91.3                                  32. E-75 + CuCO.sub.3 + S°                                                              10     10     10   2.59  90.1                                  33. E-75 + CuCO.sub.3 + S°                                                              10     10     10   2.28  91.3                                  34. PEI-3 + CuCO.sub.3 + S                                                                     10     10     10   1.98  92.4                                  35. PEI-3 + CuCO.sub.3 + S°                                                             10     10     10   1.91  92.7                                  36. PEI-6 + CuCO.sub.3 + S°                                                             10     10     10   2.80  89.3                                  37. PEI-6 + CuCO .sub.3 + S°                                                            10     10     10   3.90  85.0                                  ______________________________________                                    

                  TABLE XVIII                                                      ______________________________________                                         50% MDEA CO.sub.2 /H.sub.2 S 10/1                                                                                 Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhib-                                Compound        PPM    PPM    PPM  MPY   ition                                 ______________________________________                                         1. Blank                           20.19                                       2. Blank                           20.63                                       3. Blank                           19.51                                       4. EA-10        10                 1.54  92.3                                  5. "            10                 2.44  87.9                                  6. "            1000               1.25  93.8                                  7. "            1000               1.25  93.8                                  8. PEI-3        10                 1.25  93.8                                  9. "            10                 1.41  93.0                                  10. "           1000               0.30  98.5                                  11. "           1000               1.11  94.5                                  12. EA-10 + CuCO.sub.3 + S °                                                            10     10     10   1.17  94.2                                  13. "           10     10     10   1.03  94.9                                  14. PEI-3 + CuCO.sub.3 + S °                                                            10     10     10   1.03  94.9                                  15. "           10     10     10   1.18  94.1                                  16. CuCO.sub.3 + S °                                                                           10     10   11.13 44.7                                  17. "                  10     10   10.90 45.8                                  18. CuCO.sub.3         1000        7.14  64.5                                  19. "                  1000        7.59  62.3                                  20. SH-1        1000               10.16 49.5                                  21. "           1000               10.68 46.9                                  22. EA-18       1000               19.22 4.4                                   23. "           1000               18.35 8.8                                   24. EA-24.sup.(1)                                                                              1000               1.33  93.4                                  25. "           1000               1.25  93.8                                  26. FO-3        1000               7.52  62.6                                  27. "           1000               7.81  61.2                                  28. RCC-9       500                8.98  55.3                                  29. "           500                8.69  56.8                                  30. RCC-9 + NH.sub.4 SCN                                                                       500    50          9.06  54.9                                  31. "           500    50          8.77  56.4                                  32. RCC-9 + NH.sub.4 SCN +                                                       EA-10         500    50     10   5.97  70.3                                  33. "           500    50     10   6.26  68.9                                  34. "           500    50     1000 1.55  92.3                                  35. "           500    50     1000 1.10  94.5                                  ______________________________________                                          .sup.(1) Union Carbide polyamine D                                       

                  TABLE XIX                                                        ______________________________________                                         40% MIPA H.sub.2 S/CO.sub.2 9/1                                                                                   Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhib-                                Compound        PPM    PPM    PPM  MPY   ition                                 ______________________________________                                         1. Blank                           14.73 2.2                                   2. Blank                           15.25 -1.3                                  3. Blank                           15.18 -0.8                                  4. E-100        1000               3.24  78.5                                  5. "            1000               3.17  78.9                                  6. E-75         1000               4.05  73.1                                  7. "            1000               4.05  73.1                                  8. PEI-3        1000               1.18  92.2                                  9. "            1000               1.70  88.7                                  10. PEI-6       1000               3.25  78.4                                  11. "           1000               3.32  78.0                                  12. KW-17       1000               6.49  56.9                                  13. "           1000               5.74  61.8                                  14. CuCO.sub.3  1000               2.80  81.4                                  15. "           1000               2.95  80.4                                  16. CuCO.sub.3 in 50% DEA                                                                      10                 12.89 14.3                                  17. "           10                 12.52 16.8                                  ______________________________________                                    

                  TABLE XX                                                         ______________________________________                                         50% DEA H.sub.2 S/CO.sub.2 /COS 8/1/1                                                                             Corro-                                                                               Per-                                                                     sion  cent                                                                     Rate  Inhibi-                               Compound        PPM    PPM    PPM  MYP   ition                                 ______________________________________                                         1. Blank                           47.89 -0.0                                  2. Blank                           47.74 0.3                                   3. Blank                           48.03 -0.3                                  4. E-100        1000               1.39  97.1                                  5. E-100        1000               1.47  96.9                                  6. E-75         1000               1.47  96.9                                  7. E-75         1000               1.69  96.5                                  8. PEI-3        1000               1.17  97.6                                  9. PEI-3        1000               1.17  97.6                                  10. PEI-6       1000               1.55  96.8                                  11. PEI-6       1000               1.99  95.8                                  12. TRT-3       1000               2.06  95.7                                  13. TRT-3       1000               2.14  95.5                                  14. OA-70       2000               33.67 29.7                                  15. OA-70       2000               35.35 26.2                                  16. CuCO.sub.3 in DEA + S°                                                              10     10          59.52 -24.3                                 17. CuCO.sub.3  in DEA + S°                                                             10     10          66.60 -39.1                                 18. CuCO.sub.3  1000               8.70  81.8                                  19. CuCO.sub.3  1000               8.04  83.2                                  20. E-100 + CuCO.sub.3 + S°                                                             10     10     10   3.24  93.2                                  21. E-100 + CuCO.sub.3 + S°                                                             10     10     10   2.81  94.1                                  22. E-100       10                 19.23 59.8                                  23. E-100       10                 16.58 65.4                                  24. PEI-3       10                 2.59  94.6                                  25. PEI-3       10                 2.95  93.8                                  26. PEI-3 + CuCO.sub.3 + S°                                                             10     10     10   2.20  95.4                                  27. PEI-3 + CuCO.sub.3 + S°                                                             10     10     10   2.21  95.4                                  28. 1,2-polypropyleneimine                                                                     1000               7.96  83.4                                  29. 1,2-polypropyleneimine                                                                     1000               7.22  84.9                                  ______________________________________                                     

What is claimed is:
 1. A corrosion inhibited aqueous N-methyldiethanolamine or diethanolamine acid gas treating solution consisting essentially of (1) an amine compound or mixture of compounds having the formula ##STR3## wherein n is an integer from 1 to 3, m is an integer 2 to an integer to yield a molecular weight of about 800 and each R represents a member selected from the group consisting of --H, --C_(n),H_(2n'),OH, C_(n),H_(2n'), or --C_(n),H_(2n'),N(R₃)R₄, n' is an integer from 1 to 2, and wherein R₁ R₃ and R₂ R₄ are joined together and n' is 2; said compound being present in about 10 to about 2000 parts per million parts treating solution; (2) copper or a copper ion yielding compound in from 0 to 1000 ppm; and (3) sulfur or a sulfur atom yielding compound in from 0 to 1000 ppm.
 2. The corrosion inhibited composition of claim 1 wherein the amine compound is polyethylene polyamine mixture having an average molecular weight of about 250-300.
 3. The corrosion inhibited composition of claim 1 wherein the amine compound is polyethylenimine having a molecular weight of about
 600. 4. The corrosion inhibited composition of claim 1 wherein the amine compound is polyethylenimine having an average molecular weight of about
 300. 5. The corrosion inhibited composition of claim 1 wherein the amine compound is a polyethylene polyamine having an average molecular weight of about 250-300.
 6. The corrosion inhibited composition of claim 1 wherein the amine compound is tris(aminoethyl)amine, mixed branched-linear.
 7. The corrosion inhibited composition of claim 1 wherein the amine compound is a mixture of 35 to 45 weight percent diethylenetriamine, 10-15 weight percent triethylenediamine ##STR4## and 5 to 15 percent piperazine.
 8. The corrosion inhibited composition of claim 1 wherein the amine compound is pentaethylenehexaamine.
 9. The corrosion inhibited composition of claim 1 wherein the amine compound is a polymeric mixture of triethylenetetraamine and divinylbenzene.
 10. The corrosion inhibited composition of claim 1 wherein the amine compound is the reaction product of divinylbenzene, ethylvinylbenzene and diethylenetriamine.
 11. The corrosion inhibited composition of claim 1 wherein the amine compound is diethylenetriamine.
 12. The corrosion inhibited composition of claim 1 wherein the amine compound is methylchloride quaternary salt of divinylbenzene diethylenetriamine.
 13. The corrosion inhibited composition of claim 1 wherein the amine compound is tetraethylene pentaamine.
 14. The corrosion inhibited composition of claim 1 wherein the amine compound is a solids free mixture of 8-9 weight percent tetraethylene pentamine, 30-35 weight percent pentaethylene hexamine and 55 weight percent hexaethylene heptamine and the balance branched and cyclic isomers having an average molecular weight of about 250 to
 300. 15. The corrosion inhibited composition of claim 1 wherein the amine compound is a mixture of 85 weight percent aminoethyl piperazine and 15 weight percent diethylenetriamine. 